Heard an Acting Chancellor had a large snake (8)
I believe the answer is:
anaconda
'large snake' is the definition.
(I've seen this before)
'heard an acting chancellor had a' is the wordplay.
I cannot really understand how this works, but
'an' could be 'a' and 'a' is found in the answer.
'acting' could be 'on' (I've seen this in other clues) and 'on' is present in the answer.
'had' could be 'd' (I've seen this in other clues) and 'd' is present in the answer.
'a' is within the answer.
This may be the basis of clue (or it may be nonsense).
(Other definitions for anaconda that I've seen before include "Boa constrictor" , "cold-blooded killer" , "S. Am. constrictor snake" , "Strangler" , "One may put squeeze on" .)